Question: Is ${399664}$ divisible by $4$ ?
A number is divisible by $4$ if the last two digits are divisible by $4$ . [ Why? We can rewrite the number as a multiple of $100$ plus the last two digits: $ \gray{3996} {64} = \gray{3996} \gray{00} + {64} $ Because $399600$ is a multiple of $100$ , it is also a multiple of $4$ So as long as the value of the last two digits, ${64}$ , is divisible by $4$ , the original number must also be divisible by $4$ Is the value of the last two digits, $64$ , divisible by $4$ Yes, ${64 \div 4 = 16}$, so $399664$ must also be divisible by $4$.